Heat exchanger (fluid cooler) tube plug



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Feb. 13, 1962 Filed Aug. 4, 1959 F. E. KNECHT HEAT EXCHANGER (FLUID COOLER) TUBE PLUG 3 Sheets-Sheet 1 IN V EN TOR. fiZrn as/ E 999E642 BY ML.%

Feb. 13, 1962 F. E. KNECHT HEAT EXCHANGER (FLUID COOLER) TUBE PLUG 3 Sheets-Sheet 2 Filed Aug. 4, 1959 INVENTOR. [Zrres/E l'fzfrfi/ BY 1-.Mw

Feb. 13, 1962 F. E. KNECHT HEAT EXCHANGER (FLUID COOLER) TUBE PLUG 3 Sheets-Sheet 5 Filed Aug. 4, 1959 M MW m 6 M F w N NR 8 3 m 3 QN 7 [E\\\\\ J WW R %WNN% M\ W R R United States Patent Oflflce 3,020,929 Patented Feb. 13, 1962 3,020,929 HEAT EXCHANGER (FLUID COOLER) TUBE PLUG Forrest E. Knecht, Catawba Ave., Newfield, NJ. Filed Aug. 4, 1959, Ser. No. 831,681 4 Claims. (Cl. 138-89) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to tube plugging devices and more particularly to tube plugging devices which are particularly well adapted for plugging the open ends of heat exchanger tubes or the like.

Plugging the ends of a leaking or completely fractured heat exchanger tube to temporarily remove the tube from use or service becomes a relatively simple procedure when the fluid pressure within the tube exceeds the fluid pressure outside of the tube, i.e., exceeds the pressure of the fluid in which the tube is immersed or the pressure of the surrounding medium. In this particular situation, an ordinary or conventional tapered plug can be driven into both ends of the tube to not only prevent the flow of fluid through the tube but also to prevent the leakage of fluid between the tube and the tube sheet or header. The differential pressure acting on the plug will constantly urge the plug into engagement with the end of the tube and thus rigidly retain the plug in its desired position of intended use.

On the other hand, when the pressure of the medium in which a heat exchanger tube is immersed exceeds the pressure of the fluid circulating within the tube and the tube develops a leak or becomes completely fractured, a conventional tapered plug cannot be successfully employed to remove the tube from service. In this particular situation, the surrounding medium will enter the tube and the differential pressure created thereby will act on the plug and blow or remove the plug from the end of the tube. When such a differential pressure exists, it becomes imperative therefore that means be provided to rigidly anchor the plug within the end of the tube.

Accordingly, one object of the present invention is to prevent a plug from being removed or blown from the end of a heat exchanger tube or the like by a differential pressure acting thereon.

Another object of the invention is to plug the end of a heat exchanger tube or the like immersed in a high pressure medium.

Another object of the invention is to rigidly anchor a plug in the end of a heat exchanger tube or the like without damaging the tube sheet or header.

Another object of the invention is to rigidly anchor a plug in the end of a heat exchanger tube or the like by radially deforming a portion of the tube.

In conformity with these objects, the preferred embodiment of the invention is characterized by an elongated rod having an expander head on one end thereof and terminating at the opposite end thereof in a threaded portion. The rod is adapted to slideably carry a split-sleeve or the like together with a tapered plug with the opposing ends of the split-sleeve end plug being castellated t provide a slideable connection therebetween. In use, the splitsleeve is placed or slipped on the rod and is slid therealong until one end thereof abuts the expander head on the rod. The rod and the split-sleeve carried thereby are then inserted a predetermined distance into the open end of the tube to be plugged. The tapered plug is then placed on the rod and inserted by hand into the open end of the tube followed by the application of a take-up nut to the threaded portion of the rod.

With the unit assembly of the rod, split-sleeve and plug carried within the tube, the take-up nut is then turned along the threaded portion of the rod to move the expander head on the rod axially of the split-sleeve and expand the split-sleeve into contact with the inner periphery of the tube. This expansion of the split-sleeve in turn produces a radial expansion of the tube at a predetermined point or position to thereby rigidly anchor the rod within the tube. The take-up nut is then removed from the threaded portion of the rod and the tapered plug is thereafter forcibly driven into the open end of the tube to provide an effective sealing engagement between the plug and tube. A sealing means and a cap nut are then applied to the threaded portion of the rod to rigidly anchor or retain the plug in sealing engagement in the open end of the tube and prevent the leakage of fluid between the rod and plug.

The above-mentioned and other objects of the present invention will become readily apparent to those skilled in the art from the following detailed description of a specific embodiment thereof taken in connection with the accompanying drawings, wherein:

FIG. 1 is a vertical section through a heat exchanger employing the plugging device of the present invention;

FIG. 2 is a perspective view of the expansible means or split-sleeve utilized in the specific embodiment of the invention;

FIG. 3 is a perspective view of the plug;

FIG. 4 is a longitudinal section through a heat exchanger tube showing the unit assembly of the rod, the split-sleeve, the plug and the take-up nut prior to expansion of the split-sleeve;

FIG. 5 is another longitudinal section through the heat exchanger tube showing the split-sleeve in the expanded position and the rod rigidly anchored within the tube;

FIG. 6 is another longitudinal section through the heat exchanger tube showing the plug being driven into the open end of the tube;

FIG. 7 is another longitudinal section through the heat exchanger tube showing the final assembly of the components of the plugging device with the plug thereof being rigidly anchored in sealing engagement within the end of the tube; and

FIG. 8 is a fragmentary perspective view showing another embodiment of the split-sleeve.

Referring more particularly to FIG. 1, there is shown a heat exchanger 10 of the fluid-cooler-type which includes a housing or the like 12 defined by a top wall 14, a bottom wall 16, and an end wall 18. The end of housing 12 opposite end wall 18 includes another end wall 20 which in this particular instance takes the form of a tube sheet or tube header. Tube sheet 20 is rigidly connected to the housing top and bottom walls 14 and 16 by a plurality of bolts 26 (only two shown) which extend through aligned holes or passages (not shown) in the tube sheet and flanges 22 and 24 on the top and bottom walls, respectively. A sealing means 28 in the form of a packing or the like is carried between the opposing surfaces of the tube sheet 20 and the flanges 22 and 24 to insure a substantially leak proof connection between the tube sheet 20 and the top and bottom walls 14 and 16 of the housing,

Inasmuch as the heat exchanger 10 in this particular illustration of the invention is of the fluid-cooler-type,

the housing 12 thereof carries or receives a high temperature and high pressure fluid 30 which high temperature and high pressure fluid 30 is circulated through the housing. Housing 12 is accordingly provided with an inlet 32 in the end wall 18 thereof and the inlet 32 is adapted to receive fluid from a conduit or the like 34 which communicates with a high temperature and high pressure fluid source (not shown).- Housing end wall 18 is counterbored at 36 to provide a seat for the end of conduit 34 and any suitable means (not shown) may be employed to rigidly connect the conduit 34 to housing end wall 18 and alsoto provide an effective sealing arrangement. Tube sheet is provided with a fluid outlet 38 therein which in turn communicates with an outlet conduit 40. The tube sheet 20 is likewise counterbored at 42 to receive one end of the outlet conduit and the outlet conduit 40 is similarly connected to the tube sheet by any suitable means (not shown) which will afford both a rigid connection and an effective seal.

The high temperature and high pressure fluid 30 being circulated within heat exchanger housing 12 is cooled or reduced in temperature by another medium of some suitable type which is adapted to be circulated through the housing 12 in a plurality or bundle of tubes. In this particular instance, only three of such tubes 44, 46 and 48 are shown in the bundle for the purpose of illustration, although it will be appreciated that in practice the heat exchanger 10 could and would in most applications contain a tube bundle consisting of many more tubes. The tubes 44, 46 and 48 are substantially U-shaped and the terminal portions thereof are carried by or secured to the tube sheet 20. The specific mounting of the tubes in the tube sheet 20 is identical for each tube and can best be explained with reference to tube 44 wherein it can be seen that the tube sheet 20 is provided with a pair of holes or passages 50-50 therein, each of which is counterbored at 52-52. The terminal portions of the tube- 44 are received and secured within the passages 50-50 by being rolled into the passages with the tube wall of these terminal portions being deformed at 53-53 to the contour of the counterbores 52-52 and the ends of the tube being provided with flanges or lips 54-54 thereon which sealingly engage the outside face 56 of the tube sheet 20. Being so deformed and flanged, the tube 44 is thus rigidly connected to the tube sheet 20 and is also expanded into sealing engagement therewith to prevent the leakage of high pressure fluid between the terminal portions of the tube and tube sheet.

Tubes 44, 46 and 48 are supported intermediate their ends by a plurality of sub-headers or support members 58 (only two shown) which extend substantially transversely of the housing 12 and are secured to the housing walls 14 and 16 by any suitable means (not shown). Tube support members 58 are each provided with a plurality of passages therein (no reference numerals) to accommodate the passage therethrough of the tubes 44, 46 and 48 and the tubes may be secured to the support members 58 by any suitable means (not shown) such as welding, brazing or the like. Each support member is also provided with an enlarged aperture or port 60 therein to permit the flow of fluid through the housing 12.

The inlet ends of tubes 44, 46 and 48, i.e. the ends of the tubes above passage 38in tube sheet 20 in FIG. 1, are adapted to be supplied with a suitable cooling medium from an inlet manifold or the like (not shown) which in this particular instance is adapted to be secured to the outer face 56 of tube sheet 20. This inlet manifold (not shown) is shaped to enclose all of the inlet ends of the tubes in the tube bundle and may be secured to the outside face 56 of the tube sheet by any suitable means. The inlet manifold in this specific embodiment of the invention is adapted to supply the tubes 44, 46 and 48 with water at a relatively low pressure and the manifold may be connected by any suitable means to a water source (not shown). An outlet manifold (not shown) similar in construction to the inlet manifold is also carried by the tube sheet to provide a common receptacle for receiving the cooling water or the like discharged from the outlet ends of the tubes in the tube bundle,

It will also be noted in FIG. 1 that both ends of tube 44 are plugged with a pair of plugging devices 62 and 64 contemplated by the present invention. Both of the plugging devices 62 and 64 are rigidly secured within the, ends of tube 44 and both plugging devices 62 or 64 are identical in construction and application. For the sake of brevity, only one of the plugging devices 64 will be described in detail immediately hereinafter.

Referring now to FIGS. 2, 3 and 4, the plugging device 64 of the present invention includes an elongated rod means or rod 66 having an expander means or expander 68 in the form of a substantially frusto-conical-shaped head on one end thereof and terminating in a threaded portion 70 at the opposite end thereof. Rod 66 preferably is selected of a predetermined length and the expander head 68 thereon is of necessity limited to a maximum permissible diameter as will be discussed more in detail hereinafter.

Plugging device 64 is also comprised of an expansible means or expansible member which in this specific embodiment of the invention takes the form of a split-sleeve or the like 72. The split-sleeve 72 is adapted to be slideably carried by the rod 66 and is comprised of a substantially cylindrical head or the like 74 to which is secured a plurality of annularly arranged sleeve members, four in number in this particular instance although only three of the sleeve members 76, 78 and 80 are shown. The sleeve members extend substantially axially of the cylindrical head 74 and in this particular embodiment of the split-sleeve 72 are integrally formed with the head 74. The free end of each sleeve member carries an enlarged bearing means or bearing element 82 (only three shown) and the bearing elements are in this instance substantially triangular-shaped in cross-section. The maximum outside diameter defined by the bearing elements 82 is of importance as will be discussed more in detail hereinafter.

The head 74 of sleeve 72 also carried a plurality of castellations or castellation members which extend substantially axially of the head 74. In this particular instance, the head 74 is provided with four castellations thereon 84, 86, 88 and 90 and the castellations are integrally formed with the head. The castellations 84, 86, 88 and 90 are annularly arranged on head 74 and are spaced substantially 90"- apart, which arrangement and spacing defines four spaces or slots (no reference numerals) that separate the castellations. The castellations 84, 86, 88 and 90 are all identical in structure and are also made of a predetermined length for a purpose to be discussed more indetail hereinafter. It will also be noted that head 74 of sleeve 72 is provided with an axial bore 92 therein to accommodate the passage therethrough of rod 66.

Referring now to FIGS. 3 and 4, the tube plugging device furthermore includes a plug means or plug which in this specific embodiment of the invention takes the form of a tapered cylindrical plug 94 having an axial bore 96 therein to accommodate the passage therethrough of rod 66. The larger end of plug 94 terminates in a flat end wall 98 while the opposite end thereof is provided with a plurality of castellations or castellation members thereon. In this particular instance as in the construction of split-sleeve 72, plug 94 is provided with four identical castellations 100, 102, 104 and 106 thereon and the castellations are integrally formed with the plug. The four castellations are annularly arranged on the plug 94 and are spaced substantially 90 apart, which arrangement and spacing also defines four spaces or slots which separate the castellations. The castellations 100, 102, 104 and 106 are also made of a predetermined length. It will furthermore be noted that plug 94 is provided with a pair of opposed flats or flat surfaces 108-108 there on adjacent end wall 98.

In operation or use to plug a tube such as tube 44 in FIG. 4, the expansible sleeve 72 is first slipped or placed on rod 66 and is slid along the rod until the ends of the four sleeve elements of sleeve 72 abut the frusto-conicalshaped head 68 on the rod. The frictional engagement between the four sleeve elements and the frusto-conicalshaped head 68 will retain the sleeve 72 in this position members.

on the rod 66. The rod 66 and sleeve 72 are then insented into the open end of tube 44 a predetermined distance or to the position shown in FIG. 4 wherein it can be seen that the bearing elements 82 are positioned within tube 44 slightly in advance or forward of the inside wall 110 of tube sheet 20. It will also be noted that the tips or peripheries of the bearing elements 82 are in engagement with the inner periphery of tube 44. Bearing elements 82 are dimensioned in this particular instance such that their maximum outside diameter will provide a snug fit within tube 44 when the sleeve 72 is abutting the frusto-conical-shaped head 68 on rod 66.

With rod 66 projecting from the open end of tube 44, the plug 94 is then placed or slipped thereon and inserted by hand into the open end of the tube. The plug 94 is dimensioned or tapered in this particular instance so that approximately 40% of the length of the plug 94 will be carried within the tube when the plug is inserted by hand. With the plug 94 so positioned, it will be noted that there is a slight overlap between the castellations on the plug 94 and the castellations on the splitsleeve 72, the castellations thus providing a slideable connection between the plug 94 and split-sleeve 72. In placing the plug 94 within the open end of tube 44, the plug must be positioned so that the castellations on the plug ,to mention that it is preferable to construct the castellations on both the plug and split-sleeve such that there is a close tolerance fit between the castellations on the two This close tolerance fit will obviously serve to minimize any relative rotation between the plug 94 and sleeve 72.

After the insertion of the plug 94, "a take-up nut 112 is then applied to the threaded portion 70 of rod 66 and turned therealong until it abuts the end Wall 98 of the plug. The expansible sleeve 72 is now ready to be expanded into contact with the inner periphery of tube44 to anchor the rod 66 within the tube.

To anchor rod 66 within the tube, referring now to FIGS. 4 and 5, a wrench or the like (not shown) is applied to the flats 108108 on plug 94 followed by the placement of another wrench (not shown) on the take-up nut 112. With the plug 94 being held against rotation by the wrench, the take-up nut 112 is then turned and threaded inwardly on rod 66 to move the rod 66 axially of the tube 44 toward the open end thereof, or from right to left as shown in FIGS. 4 and 5. This axial movement of rod 66 will move the expander head 68 thereon within the split-sleeve 72 which in turn will expand the bearing members 82 of the sleeve into engagement with the inner periphery of the tube 44 to thus radially expand or deform the tube 44 at point 114 and rigidly anchor the rod 66 within the tube. In this specific embodiment of the invention, it will be noted that the tube 44 is radially expanded at point 114 in close proximity to the rear or inner face 110 of the tube sheet 20 or at a point adjacent to where the tube 44 enters the passage 50 in the tube sheet 20. Radial expansion of the tube 44 at this point will obviously provide a more rigid anchor between the tube 44 and the rod 66 and will also serve to enhance the sealing engagement between the tube 44 and the wall of the passage 50 in the tube sheet. The amount or degree of deformation of tube 44 to produce a rigid anchor between the rod 66 and tube 44 will of course vary with the particular material of which the tube 44 is made. A tube made of a hard material would require less deformation than a tube made of a soft material to rigidly anchor the rod 66 and consequently would result in less travel of the take-up nut 112.

After the rid 66 is rigidly anchored within the tube as shown in FIGS. 4 and 5, the take-up nut 112 is unthreaded or removed from the rod 66 and the plug 94 is then forced or driven (FIG. 6) into the open end of tube 44 to provide a tight sealing engagement between the outer periphery of the plug and the inner periphery of the tube. In this specific embodiment of the invention (FIG. 6), plug 94 is driven into tube 44 such that approximately one half of the length of the plug is carried within the tube, although it will be appreciated that the depth of insertion of the plug necessary to provide an eifective seal between the plug and tube will vary in any given instance and will be governed for the most part by the degree or amount of taper on the plug and the specific materials of which the tube and plug are made. With the plug 94 seated as shown in FIG. 6, it will be noted that the castellations on the plug are not in engagement with the head 74 on the split-sleeve 72 or, expressed in another manner, that the plug is still capable of being driven further into the tube before abutting the split-sleeve 72. The specific amount of additional insertion of the plug will of course be determined mainly by the specific or predetermined length of the castellations on the plug 94 and the split-sleeve 72, which predetermined length in this instance will permit an additional plug travel equal to approximately 20% of the predetermined length of the castellations. This space for additional plug travel will permit the plug 94 to be driven further into the tube in the event that the fluid within the tube should undergo an increase in pressure whereupon a tighter sealing engagement between the plug and the tube would be required. Viewing FIG. 6, it will also be noted that the seated plug 94 will also urge or expand the outer periphery of tube 44 into tight sealing engagement with the inner wall of passage 50 in tube sheet 20. Thus, when plug 94 is driven into the open end of tube 44, it not only prevents the leakage of high pressure fluid between the plug and the inner periphery of the tube but also prevents the leakage of high pressure fluid between the tube 44 and the tube sheet 20.

Any suitable means may be employed to drive the plug 94 into the open end of tube 44 although in this specific embodiment of the invention the plug 94 is adapted to be driven into the tube 44 by means of a driving fixture or driving means 116 (FIG. 6). The driving fixture is comprised in this instance of a substantially cylindrical member 118 having an enlarged recess 120 therein and terminating at one end thereof in a substantially frusto-conicalshaped head 122. In use, one end of the driving fixture 116 is placed against the end 98 of the plug 94 as shown in FIG. 6 with the end of the rod 66 being received in the enlarged recess 120. When the head 122 of the fixture is stuck with a hammer or the like (not shown), the plug 94 will be driven into the tube. The enlarged recess 120 in the fixture is of sufiicient depth to accommodate ,the added length of rod which will project beyond the end 98 of plug 94 when the plug is fully driven into the tube, the added length of rod 66 being shown in phantom and designated by reference numeral 124.

After the plug 94 is driven into the tube to the desired depth, it is preferable to remove or cut-off a portion of the added length of the rod projecting beyond the end 98 of the plug 94, more specifically to cut-off the portion 124 of the rod shown in phantom. Accordingly, in this specific embodiment of the invention, the take-up nut 112 is then re-applied (not shown in the drawings) to the threaded portion 70 of the rod 66 and turned along the rod until it abuts the end 98 of the plug 94. The threaded portion of the rod projecting beyond the take-up nut 112 is then cut-off with a hack saw or the like to thereby provide a predetermined length of rod projecting beyond the end 98 of the plug 94. The take-up nut 112 thus serves as a means to measure the excess length of rod to be removed although it will be appreciated that any other suitable measuring means could be successfully employed.

After removing the excess length of rod 66, now referring to FIG. 7, means is then applied to the threaded portion of the rod for both preventing the leakage of fluid between the rod 66 and the bore 96 in the plug 94 and rigidly anchoring the plug 94 in the end of tube 44. Accordingly, in this specific embodiment of the invention, a

seal means in the form of a gasket or the like 126 is applied to the threaded portion 70 of the rod followed by the application of a cap-nut 128 thereto. The gasket 126 in this instance is substantially identical in diameter to the maximum diameter of the plug 94 and may be made of any suitable material such as copper, aluminum or steel. The cap-nut 128, in this specific embodiment of the invention is comprised of a body portion 131} having a threaded, substantially axially extending passage 132 therein for, receiving the threaded portion 70 of the rod 66 and provided with an annular recess 134 in one end defining an annular flange 136 on one end thereof. The annular recess has a predetermined diameter and in function serves as a seat for both the gasket 126 and the end 98,, of the plug 94., The cap-nut 128 may be of any suitable cross-sectional configuration (not shown) such as square or hexagonal to accommodate the reception of a Wrench or the like (notshown).

In operation, the cap-nut 128 is turned axially along the threaded end 70 of the rod 66 until the gasket 126 is sufficiently compressed and urged into tight sealing engagement with the end 98 of the plug 94. With the capnut 128 so positioned on the threaded portion 70 of rod 66, and abutting the end 98 of the plug 94 through the medium of the gasket 126, the cap-nut 128 will prevent any relative movement between the plug 94' and rod 66 and thus rigidly retain or anchor the plug 94 in sealing engagement in the end of the tube 44, Radial deformation of the gasket 126 will be limited by the annular flange 136, on the cap-nut 128 and the radial deformation of the gasket will serve to urge the outer periphery of the gasket into tight sealing engagement with the inner periphery of the flange to thus insure a more positive seal between the cap-nut- 128 and the gasket126 It will be noted in FIG. 7 that the use of the plugging device of the present invention will in no way damage the tube sheet or header 20. The outer face 56 of the tube sheet will not be damaged by the insertion of plug 94 and the radial deformation of tube 44 at point 114 will not damage either the tube sheet innerface 110 or the inner wall of passage 50. A new tube can be inserted into the tube sheet 20 after removal of a leaking or completely fractured tube Without alterations or repair of any kind to the tube sheet.

The embodiment of the split-sleeve shown in FIG. 8 differs from the embodiment shown in FIG. 2 in that the bearing members 82 thereof are hardened and serrated or provided with peripheral teeth 138 thereon. The teeth 138 will provide a biting engagement between the hearing members 82 and the inner periphery of a tube and 8 will thus insure a more rigid anchor between the rod and tube in many applications of the plugging device.

While the plugging device of the present invention has been shown and herein described in connection with plugging the end of a heat exchanger tube or the like, it will be apparent to those skilled in the art that the plugging device could also be successfully employed to plug any other type of tube, conduit, pipe or the like which is adapted to carry a high pressure fluid. Furthermore, it will be obvious that many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A device for plugging the open end of a tube secured in a wall plate comprising a rod having an enlarged tapered head on one end, an expandable metallic sleeve slideably carried on said rod having a surface adapted to receive said tapered head of said rod and to be expanded thereby with axial movement of said rod in one direction, said rod and sleeve thereon being adapted for insertion into said tube, an enlarged portion on said sleeve adapted to grip the inner surface of said tube at a point therein beyond said plate with expansion of said sleeve and thereby anchor same, a tapered plug adapted to be wedged into the end of said tube in sealing engagement therewith slideably carried on said rod, the other end of; said rod extending through said plug, means on opposed ends of said plug and sleeve interconnecting against rotation while permitting axial movement relative each other, and retaining means on the other end of said rod for securing said plug on said rod in sealing engagement with said tube.

2. The device of claim 1 wherein said means on the opposed ends of said sleeve and plug take the form of castellations.

3, The device of claim 2 wherein said enlarged portion on said sleeve is serrated to prevent rotation thereof while P rm t aa axi l ma eme 4 The device of claim 3 including seal means on said rod between said plug and said retaining means.

References Cited in the file of this patent UNITED STATES PATENTS 2,856,963 I-loerter Oct. 21, 1958 2,867,243 Bowan Jan. 6, 1959 2,937,666 Maisch May 24, 1960 FOREIGN PATENTS 325,718 Germany Sept. 17, 1920 

